Method and system for transporting and storing at least two wind turbine blades

ABSTRACT

A transportation and storage system for at least two wind turbine blades include a first wind turbine blade and a second wind turbine blade is described. The wind turbine blades each have a root end and a tip end. The system includes a packaging system adapted to place the first wind turbine blade so that the tip end of the first wind turbine blade points in a first direction, with the tip end of the second wind turbine blade pointing in a second direction, which is substantially opposite to the first direction. The tip end of the second wind turbine blade extends beyond the root end of the first wind turbine blade, and the tip end of the first wind turbine blade extends beyond the root end of the second wind turbine blade, when the first and the second wind turbine blades are arranged in the packaging system.

This is a National Phase Application filed under 35 U.S.C. 371 as anational stage of PCT/EP2013/072386 filed on Oct. 25, 2013, anapplication claiming the benefit to British applications Nos. 1219279.5filed on Oct. 26, 2012 and 1220100.0 filed on Nov. 08, 2012; the contentof each is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates to a method of transporting or storing ofwind turbine blades as well as a transportation and storing system fortransporting at least two wind turbine blades including a first windturbine blade and a second wind turbine blade.

BACKGROUND OF THE INVENTION

Wind turbine blades used for horizontal axis wind turbines forgenerating electrical power from the wind can be rather large and maytoday exceed 70 meters in length and 4 meters in width. The blades aretypically made from a fibre-reinforced polymer material and comprisingan upwind shell part and a downwind shell part. Due to the size andfragility of these large rotor blades, the blades may be damaged duringtransport as well as during loading and unloading. Such damages mayseriously degrade the performance of the blades. Therefore, the bladesneed to be carefully packaged in order to ensure that they are notdamaged.

However, due to the increasing length of modern wind turbine blades, itis gradually becoming more complicated and expensive to transport theblades. It is not uncommon that the transportation costs amount to 20percent of the total costs for manufacturing, transporting and mountingthe wind turbine blade on the rotor of a wind turbine blade. Also, someblades are transported to the erection site through different modes oftransport, such as by truck, train and ship. Some of these modes oftransports may have restrictions on large loads, maximum heights,maximum widths, maximum distances between transport frames or supports,for instance dictated by local regulations. Therefore, there exists alogistic problem of providing transport solutions that are suitable forvarious types of transport.

Overall, there is a demand for making transport solutions simpler, saferand cheaper. The prior art shows various solutions for transporting morethan one rotor blade using a single container or other packaging system,which is an obvious way to reduce the transport costs. However, theafore-mentioned restrictions and limits may increase the difficulty oftransporting a plurality of blades using the same packaging system.

EP1387802 discloses a method and system for transporting two straightwind turbine blades, where the root end of a first blade is arranged ina first package frame, and the tip end of a second, neighbouring bladeis arranged in a second package frame that is arranged next to andconnected to the first package frame with the effect that the blades arestored compactly alongside each other in a “tip-to-root” arrangement.However, in this transport system the tip end frames support the bladesat the very tip of the blades, where they are mechanically most fragile.Further, the package frames are arranged at the root end face and theblade tip. Therefore, the distance between the package frames areapproximately equal to the length of the blades. For very long blades of45 meters or longer, this might not be possible due to local regulationsand restrictions on transport.

It is therefore an object of the invention to obtain a new method andsystem for storing and transporting a plurality of wind turbine blades,which overcome or ameliorate at least one of the disadvantages of theprior art or which provide a useful alternative.

SUMMARY OF THE INVENTION

Accordingly, there is provided a transport system for a wind turbineblade having a root end transport frame and a tip end transport frame,the frames being stackable, wherein the frames are arranged such that aroot end transport frame and at least a portion of asuccessively-stacked tip end transport frame will overlap with the rootend diameter of a wind turbine blade supported by the said root endtransport frame, and wherein the tip end transport frame is arrangedsuch that a tip end of a supported pre-bent or swept blade will bespaced from the ground.

According to an aspect of the invention, there is provided a method fortransporting or storing at least two wind turbine blades and comprisinga first wind turbine blade and a second wind turbine blade, the windturbine blades each having a root end and a tip end, wherein the methodcomprises the steps of: a) placing the first wind turbine blade so thatthe tip end of the first wind turbine blade points in a first direction,b) placing the second wind turbine blade adjacent and in immediatevicinity to the first wind turbine blade so that the tip end of thesecond wind turbine blade points in a second direction, which issubstantially opposite to the first direction. According to the firstaspect, the second wind turbine blade is in step b) arranged so that thetip end of the second wind turbine blade extends beyond the root end ofthe first wind turbine blade. The tip end of the first wind turbineblade may also extend beyond the root end of the second wind turbineblade. This will inevitably be the case, if the first wind turbine bladeand the second wind turbine blade are of the same length.

Thus, it is clear that the two wind turbine blades are arrangedsubstantially parallel to each other and oriented in oppositedirections. Since the thickness of the blades is typically decreasingfrom the root end towards the tip end, the blades can with the new“tip-to-root” layout be arranged on top of each other via frames havinga relatively small combined cross-section. Further, the new setupensures that a tip end section of the second wind turbine blade may besupported farther from the tip end than with a common frame assembly forsupporting the root of the first wind turbine blade and a tip section ofthe second blade. Thereby, the tip end section may be supported at aposition where the blade is mechanically stronger than right at the tipend.

Additionally, the new transport layout ensures that the frame assembliesmay be arranged longitudinally closer to each other, thereby being ableto abide to local regulations that may put restrictions on the maximumdistance between support frames for transport.

According to an advantageous embodiment, the first wind turbine bladeand the second wind turbine blade in steps a) and b) are stacked on topof each other, i.e. so that the second wind turbine blade is arrangedabove the first wind turbine blade. Advantageously, the first windturbine blade and the second wind turbine blade are arranged so thatchordal planes of their respective tip ends are arranged substantiallyhorizontally. By “substantially horizontally” is meant that the chordalplane may vary up to +/−25 degrees to horizontal.

In a preferred embodiment, the blades are arranged so that an upwindside (or pressure side) of the blade is facing substantially downwards.

According to an alternative embodiment, the first wind turbine blade andthe second wind turbine blade in steps a) and b) are stackedside-by-side. In such an embodiment, the first wind turbine blade andthe second wind turbine blade may advantageously be arranged so thatchordal planes of their respective tip ends are arranged substantiallyvertically. Thus, the blades may for instance be arranged so that theyare supported at their leading edges (which are mechanically strongerthan the trailing edges) via an upwardly facing receptacle.

In a stacking system for storing more than two blades, it is alsopossible to stack the blades both horizontally and vertically, i.e. in astacked array.

The method advantageously relates to transport and storage of bladeshaving a blade length of at least 40 meters, or at least 45 meters, oreven at least 50 meters. The blades may be prebent so that, when mountedon an upwind configured horizontal wind turbine in a non-loaded state,they will curve forward out of the rotor plane so that the tip to towerclearance is increased.

The first and the second wind turbine blades may be prebent. Suchprebent blades may be arranged in the tip end frames and root end framesso that they are straightened slightly or fully during transport, e.g.as shown in WO05005286 by the present applicant. However, the bladesneed not forcedly be straightened. Since the blades are supported nearthe ends and the blades are arranged with the upwind side facingdownwards, the own weight of the blade may straighten the blades due tothe gravitational forces acting on the middle part of the blade.

According to a preferred embodiment, the root end of the first windturbine blade is arranged in a first root end frame, the root end of thesecond wind turbine blade is arranged in a second root end frame, thetip end of the first wind turbine blade is arranged in a first tip endframe, and the tip end of the second wind turbine blade is arranged in asecond tip end frame. The tip end frames preferably comprise areceptacle for supporting a tip end section. Thus, the first tip endframe comprises a first tip end receptacle, and the second tip end framecomprises a second tip end receptacle. Depending on the particularsolution, the receptacle may for instance either support the pressureside of the blade or alternatively the leading edge of the blade.However, in principle the receptacle may also support the suction sideof the blade or even the trailing edge of the blade. The framesthemselves may be used as lifting tools so that two or more blades maybe lifted in one go and without imposing stress to the blades.

In a particularly advantageous embodiment, the second tip end frame isconnected, optionally detachably connected, to the first root end frame,and the first tip end frame is connected, optionally detachablyconnected, to the second root end frame. Thus, it is clear that theframes may be constructed as an integral solution comprising both a rootend frame and a tip end frame (or receptacle), or as separate frames forthe root and the tip. The latter solution has the advantage, that thesecond blade may more easily be disengaged from the first blade, simplyby detaching the tip end frames from the root end frames.

In another embodiment, the connection parts of the root end frames andthe tip end frames that connect to or fix the blade in the frame may behinged to the frame itself. This can for instance for the root beachieved by connecting a plate to the root of the blade that is hingedlyconnected to the frame. Similarly, this can be achieved by letting a tipend receptacle be hingedly connected to the tip end frame. Suchembodiments have the advantage of alleviating loads that would otherwisebe introduced to either the frames or blades due to blade deflections orthe like during transport.

In another advantageous embodiment, the first root end frame and/or thesecond root end frame is a root end bracket adapted to be attached to aroot end face of a wind turbine blade. This provides a particularlysimple solution, where the frame or bracket may be attached to forinstance a root end plate of the blade and without having to support theexterior of the blade. Thus, external damages to the outer surface ofthe blades may more easily be avoided. The tip end frames (withreceptacles) may be attached to the brackets, so that the tip endextends beyond the bracket, when the blade is inserted into the tip endframe (and receptacle).

In yet another advantageous embodiment, the first root end frame and thesecond tip end frame are connected in a L-shaped or T-shapedconfiguration so that a base of the L- or T-shaped configuration isattached to the root end of the first wind turbine blade, and atransversely extending frame part (or extremity) of the L- or T-shapedconfiguration supports a longitudinal section of the tip end of thesecond wind turbine blade. The same of course also applies to the secondroot end frame and the first tip end frame. Advantageously, the L- orT-shaped configuration is formed so that the base is a root end facebracket attached to the root end face of the first blade, and thetransversely extending frame part supports a tip end section of thesecond blade.

The frame connection is arranged so that the base of the L- orT-configuration is arranged vertically. The transversely extending framepart may be arranged to that it extends from the top or the bottom ofthe base. In this configuration the second wind turbine blade isarranged on top of the first wind turbine blade. The extremity ortransversely extending frame part may thus support either a part of thesuction side or the pressure side of the blade in an upwardly facingreceptacle. Alternatively, the extremity may extend from the side of thebase. In such a configuration, the blades are arranged side-by-side, andthe extremity or transversely extending frame part may support either apart of the leading edge or the trailing edge of the blade in anupwardly facing receptacle.

If the blades are arranged so that both blades are facing with theleading edge downwards (in the side-by-side arrangement) or with theupwind shell parts facing downwards (in the vertically stackedarrangement), it is clear that the transversely extending frame parts ofthe two frame assemblies must be arranged inversely compared to the baseframe. Thus, the two frame assemblies have slightly differentconfigurations.

The L- or T-shaped frame assembly has the advantage that thetransversely extending frame supports a larger part of the tip sections,thus better alleviating loads and possibly also minimising the necessaryoverhang of the tip part that extends beyond the root end frame.

In one embodiment, the longitudinal extent of the transversely extendingframe part is at least 1 meter, advantageously at least 1.5 meters, moreadvantageously at least 2 meters. The longitudinal section of the tipend of the blade may be supported along the entire section, or it may besupported in a plurality of discrete sections within the extremity ofthe L- or T-shaped frame assembly.

As an alternative to the L- or T-shaped frame assembly, the root endframe and the tip end frame may be arranged substantially in the sameplane.

Advantageously, a plurality of first wind turbine blades and second windturbine blades are placed in an array, and wherein the wind turbineblades each comprise a shoulder defining a maximum chord of the blade,and wherein the blades are arranged so that the maximum chord forms anangle of between 20 and 75 degrees to a horizontal plane, advantageouslybetween 22 and 73 degrees. Even more advantageously, the maximum chordforms an angle of between 15 and 35 degrees to a horizontal plane,advantageously between 20 and 30 degrees. It is clear that this stackingmethod may be advantageous to any configuration of stacking blades sideby side with the root end and tip end arranged in the same direction. Ina preferred embodiment, it is the root end of the blade that is turnedbetween 15 and 35 degrees to a horizontal plane, advantageously between20 and 30 degrees. The angle may for instance be defined by bond linesbetween an upwind shell part and a downwind shell part at the root endof the blade. In this setup, the blades in a stacked array may bearranged so that they slightly overlap with the shoulder of one bladeextending partly over an adjacent blade, so that the upwind side of oneblade near the shoulder faces down towards the downwind side near theleading edge of an adjacent blade. Thereby, it is possible to stack theblades in frames having a width corresponding to the diameter of theroot or only slightly larger, even though the chord length of theshoulder exceeds this diameter.

In another embodiment, intermediate protection members are arrangedbetween the first wind turbine blade and the second wind turbine blade.The intermediate protection members are preferably arranged at alongitudinal position between the first root end frame and the secondroot end frame. Advantageously, the intermediate protection members arearranged near the tip end frames so as to provide additional support toa tip end section of the wind turbine blade. The protection meansprevent the blades from being damaged due to bending or the bladesimpacting each other. The intermediate protection members areparticularly advantageous, when the blades are stacked on top of eachother. In such a setup, the intermediate protection members may be usedas support for supporting an additional tip end section of one blade andmay transfer loads from the tip end of the upper blade to themechanically stronger root region of the lower blade. Additionalprotection members may be arranged below the lowermost blade in astacked array and a support platform or the ground. The additionalprotection member is advantageously arranged to support an additionaltip end section of the lowermost blade, e.g. near the tip end frame ofthe lowermost blade.

The intermediate protection members may be made of a foamed polymer.

In another embodiment, a root end face of the first wind turbine bladeis arranged within 45 meters of a root end face of the second windturbine blade, advantageously within 42 meters. Accordingly, root endbrackets or frames should also be arranged at maximum 45 meters or 42meters from each other.

According to the first aspect, the invention also provides atransportation and storage system for at least two wind turbine bladesand comprising a first wind turbine blade and a second wind turbineblade. The wind turbine blades each have a root end and a tip end. Thesystem comprises a packaging system that is adapted to placing the firstwind turbine blade so that the tip end of the first wind turbine bladepoints in a first direction, and placing the second wind turbine bladeso that the tip end of the second wind turbine blade points in a seconddirection, which is substantially opposite to the first direction. Thetip end of the second wind turbine blade extends beyond the root end ofthe first wind turbine blade, and the tip end of the first wind turbineblade extends beyond the root end of the second wind turbine blade, whenthe first and the second wind turbine blades are arranged in thepackaging system. Thus, again it is clear that the system is adapted toarranging the first and the second wind turbine blades substantiallyparallel to each other and pointing tip to root but with an overhang.

According to a first embodiment, the packaging system comprises: a firstroot end frame for attachment to the root end of the first wind turbineblade, a first tip end frame for supporting a tip end portion of thefirst wind turbine blade, a second root end frame for attachment to theroot end of the second wind turbine blade, and a second tip end framefor supporting a tip end portion of the second wind turbine blade. Thesecond tip end frame may be connected, optionally detachably connected,to the first root end frame, and the first tip end frame may beconnected, optionally detachably connected, to the second root endframe. Thus, it is clear that the frames may be constructed as anintegral solution comprising both a root end frame and a tip end frame(or receptacle), or as separate frames for the root and the tip. Thelatter solution has the advantage, that the second blade may more easilybe disengaged from the first blade, simply by detaching the tip endframes from the root end frames.

In one advantageous embodiment, the first root end frame and/or thesecond root end frame are root end brackets adapted to be attached to aroot end face of the first wind turbine blade and the second windturbine blade, respectively. This provides a particularly simplesolution, where the frame or bracket may be attached to for instance aroot end plate of the blade and without having to support the exteriorof the blade. Thus, external damages to the outer surface may moreeasily be avoided. The tip end frames (with receptacles) may be attachedto the brackets, so that the tip end extends beyond the bracket, whenthe blade is inserted into the tip end frame (and receptacle).

In the tip end of the first wind turbine blade, when arranged in thefirst tip end frame, extends a first longitudinal extent beyond thefirst tip end frame, and the tip end of the second wind turbine blade,when arranged in the second tip end frame, extends a second longitudinalextent beyond the first tip end frame. In other words, the first tip endframe is adapted to package the tip end of first wind blade at a firstdistance from the tip, and the second tip end frame is adapted topackage the tip end of the tip end of the second wind turbine blade at afirst distance from the tip. The first distance and the second distancewill of course typically be approximately the same. The firstlongitudinal extent and the second longitudinal extent may be at least 2meters, advantageously at least 3.5 meters, and more advantageously, atleast 5 meters. The blade tip may even extend at least 6, 7, or 8 metersbeyond the tip end frame.

In a particular advantageous embodiment, the storage system is adaptedto stack the first and the second wind turbine blade on top of eachother. The second tip end frame may for instance be attached to a top ofthe first root end frame, and the first tip end frame is attached to abottom of the second root end frame. In this setup the blades arearranged so that chord planes of the tip ends of the blades are arrangedsubstantially horizontally. The setup may be adapted to arrange theblades with an upwind shell part substantially downwards.

In an alternative embodiment, the tip end frames are attached to sidesof the root end frames. In such a setup the chord planes of tip end ofthe blades are arranged substantially vertically, advantageously with aleading edge facing downwards.

In another embodiment, at least a first intermediate protective memberis arranged between the first wind turbine blade and the second windturbine blade. The first intermediate protective member mayadvantageously be arranged near the tip end of an upper arranged bladeof the first wind turbine blade and the second wind turbine blade.Additionally, a second protective member may be arranged below the lowerof the two wind turbine blades. In a stacked array, this blade will thenalso be an intermediate protective member arranged between two blades.Further, a protective member may be arranged below the lowermost bladein the stacked array. The intermediate protective members may be made ofa foamed polymer.

It is clear that some of the provided solution may also be used forother configurations of transporting and storing blades, e.g. withoutthe tip overhang.

Thus, according to a second aspect, the invention provides a method fortransporting or storing at least two wind turbine blades and comprisinga first wind turbine blade and a second wind turbine blade, the windturbine blades each having a root end and a tip end, wherein the methodcomprises the steps of:

-   a) placing the root end of the first wind turbine blade in a first    root end frame,-   b) placing a tip end section of the first wind turbine blade in a    first tip end frame,-   c) placing the root end of the second wind turbine blade in a second    root end frame, so that the second root end frame is arranged near    the first tip end frame with the first tip end frame substantially    above the second root end frame,-   d) placing a tip end section of the second wind turbine blade in a    second tip end frame, so that the second tip end frame is arranged    near the first root end frame with the second tip end frame    substantially below the first root end frame, wherein the method    comprises the additional step of arranging an intermediate    protection means between the first wind turbine blade and the second    wind turbine blade.

According to another aspect, the invention also provides atransportation and storage system for at least two wind turbine bladesand comprising a first wind turbine blade and a second wind turbineblade, the wind turbine blades each having a root end and a tip end,said system comprising a packaging system that is adapted to placing thefirst wind turbine blade so that the tip end of the first wind turbineblade points in a first direction, and placing the second wind turbineblade so that the tip end of the second wind turbine blade points in asecond direction, which is substantially opposite to the firstdirection, wherein the transportation and storage system includes apackaging system that comprises:

-   -   a first root end frame for attachment to the root end of the        first wind turbine blade,    -   a first tip end frame for supporting a tip end portion of the        first wind turbine blade,    -   a second root end frame for attachment to the root end of the        second wind turbine blade, and    -   a second tip end frame for supporting a tip end portion of the        second wind turbine blade, wherein the packaging system further        comprises an intermediate protection means arranged between the        first wind turbine blade and the second wind turbine blade.

According to a further aspect, the invention provides a method fortransporting or storing at least two wind turbine blades and comprisinga first wind turbine blade and a second wind turbine blade, the windturbine blades each having a root end and a tip end, wherein the methodcomprises the steps of:

-   a) placing the root end of the first wind turbine blade in a first    root end frame,-   b) placing a tip end section of the first wind turbine blade in a    first tip end frame,-   c) placing the root end of the second wind turbine blade in a second    root end frame,-   d) placing a tip end section of the second wind turbine blade in a    second tip end frame, wherein    -   the first root end frame and the second tip end frame as well as        the first tip end frame and the second root end frame are        connected as L-shaped or T-shaped frame assemblies so that bases        of the frame assemblies are attached to the root ends of the        first and the second wind turbine blade, and extremities of the        frame assemblies support a longitudinal section of the tip ends        of the first and the second wind turbine blades.

The invention also provides a transportation and storage system for atleast two wind turbine blades and comprising a first wind turbine bladeand a second wind turbine blade, the wind turbine blades each having aroot end and a tip end, said system comprising a packaging system thatis adapted to placing the first wind turbine blade so that the tip endof the first wind turbine blade points in a first direction, and placingthe second wind turbine blade so that the tip end of the second windturbine blade points in a second direction, which is substantiallyopposite to the first direction, wherein the transportation and storagesystem includes a packaging system that comprises:

-   -   a first root end frame for attachment to the root end of the        first wind turbine blade,    -   a first tip end frame for supporting a tip end portion of the        first wind turbine blade,    -   a second root end frame for attachment to the root end of the        second wind turbine blade, and    -   a second tip end frame for supporting a tip end portion of the        second wind turbine blade, wherein    -   the first root end frame and the second tip end frame as well as        the first tip end frame and the second root end frame are        connected as L-shaped or T-shaped frame assemblies so that bases        of the frame assemblies are attached to the root ends of the        first and the second wind turbine blades, and extremities of the        frame assemblies support a longitudinal section of the tip ends        of the first and the second wind turbine blades.

Further, the invention provides a frame assembly for use in transportand storing of wind turbine blades, wherein the frame assembly comprisesa root end frame part for attachment to a root end of a first windturbine blade and a tip end frame part for supporting a tip end sectionof a second blade, wherein the root end frame part and the tip end framepart are attached in an L-shaped or T-shaped configuration.

According to a further aspect, the invention provides a transportationand storage system for at least two wind turbine blades and comprising afirst wind turbine blade and a second wind turbine blade, the windturbine blades each having a root end and a tip end as well as ashoulder defining a maximum chord of the blade, wherein the methodcomprises the steps of:

-   a) placing the root end of the first wind turbine blade in a first    root end frame,-   b) placing a tip end section of the first wind turbine blade in a    first tip end frame,-   c) placing the root end of the second wind turbine blade in a second    root end frame,-   d) placing the tip end section of the second wind turbine blade in a    second tip end frame,-   e) arranging the first and the second blade parallel to each other    so that the first root end frame is placed adjacent the second root    end frame, and the first tip end frame is arranged adjacent the    second tip end frame, wherein    the first wind turbine blade and the second wind turbine blade are    arranged so that the maximum chord of the blades form angles of    between 15 and 35 degrees to a horizontal plane, advantageously    between 20 and 30 degrees, more advantageously around 25 degrees.

It is clear that all the embodiments described with respect to a firstaspect of the invention also apply to any other aspect of the invention.

In particular, there is provided a transport system for a wind turbineblade having a tip end and a root end, the blade further having a boltcircle diameter D at said root end, wherein the transport systemcomprises:

-   -   a root end transport frame for supporting a root end of a wind        turbine blade;    -   a tip end transport frame for supporting a portion of a wind        turbine blade towards the tip end of said blade, said tip end        transport frame comprising a base frame and a support bracket        provided on top of said base frame for receiving a portion of a        wind turbine blade;    -   wherein said tip end transport frame is stackable on top of said        root end transport frame, such that the transport system is        operable to stack successive wind turbine blades in an        alternating root end to tip end arrangement;    -   wherein said root end transport frame has a height H;    -   wherein said tip end transport frame comprises a base frame        having a height h; and    -   wherein (H+h) is approximately equal to D;    -   such that a root end transport frame and the base frame of a        successively stacked tip end transport frame overlap with a root        end of a wind turbine blade supported by said root end transport        frame.

Providing tip end supports having a base height of h means that when anindividual wind turbine blade is supported on a surface using thetransport system, the tip end of such a blade is spaced from theunderlying surface via said base height. Furthermore, when in a stackedconfiguration, as the construction of the root end frame allows the tipend frame to overlap with the root end of a wind turbine blade stackedbeneath the tip end frame, the height of a stacked collection of windturbine blades using said transport system will be reduced.

By overlap, it will be understood that, by providing the tip end framewith a base height h on top of which the support bracket is located,this allows the base frame to be stacked on top of a preceding root endframe, such that the vertical height of the root end frame and the baseframe of the tip end frame are substantially equal to the root enddiameter of the supported blade.

Preferably, (0.5 D)<H<(0.9 D).

There is also provided a root end transport frame for a wind turbineblade, the blade having a tip end and a root end, the transport framehaving a height, a width, and a depth,

-   -   wherein the height of the transport frame is less than the bolt        circle diameter of a root end of a wind turbine blade to be        supported by said transport frame.

A reduced-height transport frame allows for relatively easier handlingof the transport frame, and reduces transport and handling costs of theframe when not in use supporting a wind turbine blade.

Preferably, the width of said transport frame is equal to or greaterthan the bolt circle diameter of a wind turbine blade to be supported bysaid transport frame.

Preferably, the depth of said transport frame is equal to or greaterthan one quarter of the width of the transport frame.

Providing a transport frame with such dimensions results in a stablestructure with a low centre of mass, and which is able to support a windturbine blade.

Preferably, the root end transport frame comprises:

-   -   a frame body;    -   a root end plate coupled to said frame body, said root end plate        arranged to couple with a root end of a wind turbine blade,    -   wherein said root end plate is arranged to couple with less than        ⅔ of the bolt circle of a root end of a wind turbine blade to        support said wind turbine blade on said transport frame.

As the root end plate is designed to support a wind turbine blade byonly coupling with a portion of the root end of the wind turbine blade,accordingly the height of the root end plate relative to the bolt circlediameter of the root end of the wind turbine blade may be reduced,resulting in a reduced total height of the root end transport frame.

Preferably, said root end plate comprises a substantially C-shaped bodyarranged to couple with a portion of the bolt circle of a root end of awind turbine blade.

There is also provided a root end transport frame for a wind turbineblade, the blade having a tip end and a root end, the transport framecomprising:

-   -   a frame body; and    -   a root end plate for coupling to the root end of a wind turbine        blade, wherein said root end plate is hingedly coupled to said        frame body.

By providing a hinged root plate, any bending moments due to bladedeflection or bending are prevented from being transferred to the framebody. Accordingly, the frame body may be of a relatively lighterconstruction, as it does not need to bear such relatively large forces.

Preferably, said root plate is hingedly coupled to said frame body alongthe horizontal axis.

As the angle to the vertical made by the root end of a blade may dependon factors such as the centre of gravity of the blade and the bladebending properties, accordingly the ability for the root plate to hingealong the horizontal axis allows for different angles of the blade rootend to be accommodated by the transport frame.

Additionally or alternatively, said root plate is hingedly coupled tosaid frame body along the vertical axis.

The hinging of the root plate around the vertical prevents damage to thetransport frame due to misalignment or handling issues.

Preferably, said root end plate is mounted on at least one bracket arm,said at least one arm coupled to said transport frame via a hingedjoint.

Preferably, said at least one bracket arm comprises an articulatedbracket.

The use of an articulated bracket allows for greater degrees of freedomof manipulation of the root plate, to more easily receive andaccommodate the root end of a wind turbine blade on the transport frame.

Preferably, said transport frame comprises at least a first and a secondbracket arm, wherein said first and second bracket arms are positionedon opposed sides of a notional central longitudinal axis of a windturbine blade to be mounted to said root end plate.

By positioning the bracket arms on either side of the centre point ofthe blade root end, the take up of forces from the root end of the bladeis balanced in the transport frame.

There is also provided a tip end transport frame for a wind turbineblade, the blade having a tip end and a root end, the transport framecomprising:

-   -   a frame body;    -   a tip end support bracket for supporting a portion of a wind        turbine blade towards the tip end of said blade, wherein a first        end of said tip end support bracket is hingedly coupled to said        transport frame along the horizontal axis; and    -   wherein a leading edge support lip is provided on said bracket,        said leading edge support lip arranged to receive a portion of        the leading edge of a wind turbine blade supported by said        support bracket, such that the wind turbine blade can be        pivotably moved about said hinged coupling relative to said        transport frame while supported on said bracket.

By providing a hinged coupling for the support bracket, a wind turbineblade may be adjusted relative to the frame body, to allow for correctpositioning of the wind turbine in the transport frame. The leading edgesupport lip provided on the bracket allows for the partial support ofthe wind turbine blade, preventing unwanted movement of the wind turbineblade during any such pivoting or subsequent transport.

Preferably, a second end of said support bracket may be releasablysecured to said frame body when said support bracket is received in saidframe body.

Preferably, said tip end support bracket comprises a flexible straphaving a support surface provided on said flexible strap.

The use of a flexible strap as part of the bracket allows for minoradjustments or movements of a supported wind turbine blade to beabsorbed through appropriate torsion or twisting of the strap, withoutbeing transferred to the relatively rigid frame body. Accordingly, theframe body may be of a more lightweight construction compared to priorart systems.

Preferably, the tip end transport frame further comprises a securingstrap to be fitted around a wind turbine blade received in saidtransport frame.

Preferably, the tip end transport frame is arranged to be positioned ata location toward the tip end of a wind turbine blade to be supported bythe transport system, such that a sweep or bend of the wind turbineblade from the location of said tip end transport frame to the tip endof the supported blade is less than height h of the base frame of thetip end transport frame.

The transport system is preferably used in the transport of bladeshaving a pre-bend Δy, and/or swept blades. Accordingly, locating thesupport bracket of the tip end frame above the horizontal surface by aheight h allows for such a curved blade to be supported on the groundwithout the tip end of the blade striking the ground.

Preferably, the tip end transport frame is arranged to be positionedspaced from the tip end of the blade.

Preferably, a wind turbine blade to be supported by the transport systemhas a longitudinal length L, wherein the tip end transport frame isarranged to be positioned at a distance F from the root end of saidblade, wherein (0.5 L)<F<(0.95 L), preferably (0.6 L)<F<(0.85 L).

Supporting the tip portion of the wind turbine blade at such a locationin the outboard portion of the blade, spaced from the tip end, providesa balance between effectively structurally supporting the blade, whilereducing the minimum effective wheelbase or support surface needed tosupport the total transport system.

There is further provided a method of transporting at least two windturbine blades having a tip end and a root end, the method comprisingthe steps of:

-   -   supporting a first wind turbine blade, wherein a first root end        transport frame is arranged to support the root end of said        first wind turbine blade and a first tip end transport frame is        arranged to support a portion of said first wind turbine blade        towards the tip end of said first blade, said first wind turbine        blade having a bolt circle diameter D at said root end;    -   supporting a second wind turbine blade, wherein a second root        end transport frame is arranged to support the root end of said        second wind turbine blade and a second tip end transport frame        is arranged to support a portion of said second wind turbine        blade towards the tip end of said second blade, and    -   stacking said second root end transport frame on top of said        first tip end transport frame, and stacking said second tip end        transport frame on top of said first root end transport frame,        wherein said second wind turbine blade is stacked in an        alternating root end to tip end arrangement above said first        wind turbine blade to form a unit for transport,    -   wherein at least said first root end transport frame is arranged        to have a height H,    -   wherein said first and second tip end transport frames are        arranged to support the respective first and second wind turbine        blades at a height h above the base of the first and second tip        end transport frames, and    -   wherein (H+h) is approximately equal to D,    -   such that said first root end transport frame and at least a        portion of said second tip end transport frame overlap with the        root end of said first wind turbine blade.

It will be understood that any of the above-described features may becombined in any embodiment of the transport system as described.Further, it will be understood that said tip end transport frame may beprovided separately to said root end transport frame, and vice versa.

DETAILED DESCRIPTION OF THE INVENTION

The invention is explained in detail below with reference to embodimentsshown in the drawings, in which

FIG. 1 shows a wind turbine,

FIG. 2 shows a schematic view of a wind turbine blade according to theinvention,

FIG. 3 shows a schematic view of an airfoil profile,

FIG. 4 shows a schematic view of the wind turbine blade according to anembodiment of the invention, seen from above and from the side,

FIG. 5 shows a schematic side view of a first wind turbine blade and asecond wind turbine blade stored in a packaging system according to thean embodiment of invention,

FIG. 6 illustrates how the blades are oriented in the packaging systemaccording to an embodiment of the invention,

FIG. 7 shows a schematic end view of blades stored in a stacked array ofpackaging systems according to an embodiment of the invention,

FIG. 8 shows a top view of the mutual arrangement of blades when stackedin an array,

FIG. 9 shows a schematic side view of a number of first wind turbineblades and second wind turbine blades stored in a packaging systemaccording to an embodiment of the invention with intermediate protectionmeans arranged between the blades,

FIG. 10 shows a perspective view of blades stored in a stacked array ofpackaging systems in an alternative embodiment of the invention,

FIG. 11 shows an embodiment of a root end transport frame according toan embodiment of the invention,

FIG. 12 shows an embodiment of a tip end transport frame according to anembodiment of the invention, and

FIG. 13 shows a side view of an arrangement of pre-bent wind turbineblades supported by transport systems according to embodiments of theinvention.

The present invention relates to transport and storage of wind turbineblades for horizontal axis wind turbines (HAWTs).

FIG. 1 illustrates a conventional modern upwind wind turbine accordingto the so-called “Danish concept” with a tower 4, a nacelle 6 and arotor with a substantially horizontal rotor shaft. The rotor includes ahub 8 and three blades 10 extending radially from the hub 8, each havinga blade root 16 nearest the hub and a blade tip 14 furthest from the hub8. The rotor has a radius denoted R.

FIG. 2 shows a schematic view of a first embodiment of a wind turbineblade 10. The wind turbine blade 10 has the shape of a conventional windturbine blade and comprises a root region 30 closest to the hub, aprofiled or an airfoil region 34 furthest away from the hub and atransition region 32 between the root region 30 and the airfoil region34. The blade 10 comprises a leading edge 18 facing the direction ofrotation of the blade 10, when the blade is mounted on the hub, and atrailing edge 20 facing the opposite direction of the leading edge 18.

The airfoil region 34 (also called the profiled region) has an ideal oralmost ideal blade shape with respect to generating lift, whereas theroot region 30 due to structural considerations has a substantiallycircular or elliptical cross-section, which for instance makes it easierand safer to mount the blade 10 to the hub. The diameter (or the chord)of the root region 30 may be constant along the entire root area 30. Thetransition region 32 has a transitional profile gradually changing fromthe circular or elliptical shape of the root region 30 to the airfoilprofile of the airfoil region 34. The chord length of the transitionregion 32 typically increases with increasing distance r from the hub.The airfoil region 34 has an airfoil profile with a chord extendingbetween the leading edge 18 and the trailing edge 20 of the blade 10.The width of the chord decreases with increasing distance r from thehub.

A shoulder 40 of the blade 10 is defined as the position, where theblade 10 has its largest chord length. The shoulder 40 is typicallyprovided at the boundary between the transition region 32 and theairfoil region 34.

It should be noted that the chords of different sections of the bladenormally do not lie in a common plane, since the blade may be twistedand/or curved (i.e. pre-bent), thus providing the chord plane with acorrespondingly twisted and/or curved course, this being most often thecase in order to compensate for the local velocity of the blade beingdependent on the radius from the hub.

The wind turbine blade 10 comprises a shell made of fibre-reinforcedpolymer and is typically made as a pressure side or upwind shell part 24and a suction side or downwind shell part 26 that are glued togetheralong bond lines 28 extending along the trailing edge 20 and the leadingedge 18 of the blade 10.

FIGS. 3 and 4 depict parameters, which are used to explain the geometryof the wind turbine blades to be stored and transported according to theinvention.

FIG. 3 shows a schematic view of an airfoil profile 50 of a typicalblade of a wind turbine depicted with the various parameters, which aretypically used to define the geometrical shape of an airfoil. Theairfoil profile 50 has a pressure side 52 and a suction side 54, whichduring use—i.e. during rotation of the rotor—normally face towards thewindward (or upwind) side and the leeward (or downwind) side,respectively. The airfoil 50 has a chord 60 with a chord length cextending between a leading edge 56 and a trailing edge 58 of the blade.The airfoil 50 has a thickness t, which is defined as the distancebetween the pressure side 52 and the suction side 54. The thickness t ofthe airfoil varies along the chord 60. The deviation from a symmetricalprofile is given by a camber line 62, which is a median line through theairfoil profile 50. The median line can be found by drawing inscribedcircles from the leading edge 56 to the trailing edge 58. The medianline follows the centres of these inscribed circles and the deviation ordistance from the chord 60 is called the camber f. The asymmetry canalso be defined by use of parameters called the upper camber (or suctionside camber) and lower camber (or pressure side camber), which aredefined as the distances from the chord 60 and the suction side 54 andpressure side 52, respectively.

Airfoil profiles are often characterised by the following parameters:the chord length c, the maximum camber f, the position d_(f) of themaximum camber f, the maximum airfoil thickness t, which is the largestdiameter of the inscribed circles along the median camber line 62, theposition d_(t) of the maximum thickness t, and a nose radius (notshown). These parameters are typically defined as ratios to the chordlength c. Thus, a local relative blade thickness t/c is given as theratio between the local maximum thickness t and the local chord lengthc. Further, the position d_(p) of the maximum pressure side camber maybe used as a design parameter, and of course also the position of themaximum suction side camber.

FIG. 4 shows other geometric parameters of the blade. The blade has atotal blade length L. As shown in FIG. 3, the root end is located atposition r=0, and the tip end located at r=L. The shoulder 40 of theblade is located at a position r=L_(w), and has a shoulder width W,which equals the chord length at the shoulder 40. The diameter of theroot is defined as X. Further, the blade is provided with a prebend,which is defined as Δy, which corresponds to the out of plane deflectionfrom a pitch axis 22 of the blade.

Blades have over the time become longer and longer and may now exceed alength of 70 meters. The length of the blades as well as the shape ofthe blades with respect to shoulder, twist and prebending makes itincreasingly difficult to transport the blades, in particular if aplurality of blades is to be transported and stored together. The shapeand size of the blades also puts limitations on how closely the bladescan be stored in a stacked array.

FIG. 5 shows a schematic view of first embodiment of a transportationand storage system according to the invention for transporting andstoring a first wind turbine blade and a second wind turbine blade 10.The transportation and storage system includes a packaging system thatcomprises a first frame assembly 70. The first frame assembly 70 iscomposed of a root end frame 71 in form of a root end bracket forattachment to a root end face 17 of the first wind turbine blade, and atip end frame 72 for supporting a tip end section 15 of the second windturbine blade. The first frame assembly has an L-shaped configuration,where the root end bracket 71 forms the base of the L-shaped assembly,and the tip end frame 72 forms a transversely extending frame part (orextremity) that extends from the top of root end bracket 71. The secondframe assembly 80 is also composed of a root end frame 81 in form of aroot end bracket for attachment to a root end face 17 of the second windturbine blade, and a tip end frame 82 for supporting a tip end section15 of the first wind turbine blade. The first frame assembly has anL-shaped configuration, where the root end bracket 81 forms the base ofthe L-shaped assembly, and the tip end frame 82 forms a transverselyextending frame part (or extremity) that extends from the bottom of rootend bracket 81.

In terms of the following claims, it is clear that the first frameassembly comprises the first root end frame and the second tip endframe, whereas the second frame assembly comprises the second root endframe and the first tip end frame.

Some local regulations have limitations on the maximum distance I_(f)between supports for transporting items, for instance a maximum of 42meters. The packaging system accommodates for such regulations by beingdesigned so that the tip ends of the first wind turbine blade and thesecond wind turbine blade extend beyond the root end frames 70, 80 sothat a longitudinal extent I_(o) or overhang of the tip ends extendsbeyond the root end frames 70, 80, thereby being able to transportblades of lengths exceeding the maximum distance I_(f) between supports.Further, this novel setup has the advantage that the tip end sectionsare supported at a distance from the respective tip ends, where theblades are mechanically stronger than right at the tip. Thus, theprobability of the frames damaging the blades is lowered significantly.Further, the L-shaped configuration of the frame assemblies 70, 80 isadapted to support the tip ends over a longitudinal extent of e.g. atleast 1 meter, thereby ensuring an even better support for the blades.

The tip end frames 72, 82 may advantageously comprise one or morereceptacles having an upwardly facing support face for supporting a partof the upwind side of the blade. Further, the tip end frames 72, 82 mayadvantageously be detachably coupled to the root end frames 71, 81.

In the shown setup, the blades are arranged with the pressure side (orupwind side) facing substantially downwards. Thereby, the blades arealso arranged so that the middle part of the blade is spaced furtherfrom the support surface or ground due to the prebending of the blades.However, the blades are as shown in FIG. 6 turned so that the bond lines28 as well as the chord of the shoulder 40 forms an angle α ofapproximately 25 degrees to a horizontal line 29. This has a furtheradvantage, when blades are stacked in arrays comprising first and secondframe assemblies 70, 80 and accordingly comprising an array of storedfirst and second wind turbine blades, since the blades may be stackedmore compactly than conventional systems for transporting and storingsuch blades. This is better illustrated in FIGS. 7 and 8 that showblades stacked in an array, where FIG. 7 shows an end view of thetransportation and storage system with the blades stored in the system,and FIG. 8 shows a top view of the blades in the array with the storagesystem removed from the figure in order to better illustrate the mutualarrangement of the blades.

From the end view shown in FIG. 7, it is seen that the first blades thathave their root end faces attached to the root end brackets 71 arearranged so that the shoulders of the blades 40 point slightly upwardsand to the right, whereas the second blades that have their tip endsections supported in the tip end frames 72 are arranged so that theshoulders 40 point upwards and towards the left side of the figure.Thereby, the blades can be stacked side by side in frames that are onlyslightly wider than the root diameter D of the blades.

In the top view shown in FIG. 8, it is seen that the blades are arrangedso that they slightly overlap with the shoulder 40 of one bladeextending partly over an adjacent blade, so that the upwind side of oneblade near the shoulder faces down towards the downwind side near theleading edge of an adjacent blade.

In some situations it may be advantageous to provide additional supportmembers for taking up loads from the blades, for instance by providingintermediate support members 90 between the first and the second windturbine blades. The intermediate support members 90 may advantageouslybe arranged near the tip end of the upper blade so that loads may betransferred from a tip section of the upper blade to a root section of alower blade. An additional protection member 92 may be arranged betweenthe lowermost blade in an array and the support platform or ground. Theprotection members 90, 92 may for instance be made of a foamed polymer.

With reference to FIG. 11, an embodiment of a root end transport frameaccording to an aspect of the invention is indicated generally at 100.The root end transport frame 100 comprises a frame body 102 and a rootend plate 104 coupled to the frame body 102. FIG. 11(a) illustrates afront perspective view of the transport frame 100, FIG. 11(b)illustrates a plan view of a root end plate 104 of the transport frame,FIG. 11(c) illustrates a rear perspective view of the transport frame100, and FIG. 11(d) illustrates a rear perspective view of the root endplate of the frame of FIG. 11(c).

The transport frame 100 is arranged to couple with less than the entirecircumference of a bolt circle of a wind turbine blade to be supportedby the transport frame, as this provides several advantages in terms ofstability, and transport and handling issues.

The transport frame 100 is designed to have a height H less that thebolt circle diameter of the root end of a wind turbine blade to besupported by the transport frame, and preferably to have a width Wgreater than or equal to said bolt circle diameter. The depth D_(f) ofthe frame 100 is designed to adequately support the frame 100,preferably being at least one quarter of the bolt circle diameterdistance. Such a construction provides a relatively low centre of massof the transport frame 100, and reduced the possibility of the frame 100being easily overturned, either when supporting a root end of a windturbine blade or when not supporting a blade.

The root end plate 104 is hingedly coupled to the frame body 102, via apair of projecting bracket arms 106. In the embodiment of FIG. 11, thebracket arms 106 are hinged to the frame body 102 about the horizontalaxis, but it will be understood that any suitable hinged joint may beprovided, and/or articulated brackets may be provided. The use of ahinged connection between the root end plate 104 and the frame body 102means that the plate 104 can be provided at any suitable angle to thevertical, to accommodate any bending or deflection of the root end ofthe wind turbine blade, without transferring such bending moments to theframe body 102. As a result, the frame body 102 may be of a relativelylightweight construction, as it does not have to bear such relativelylarge bending moments from the blade root end.

Preferably, at least two bracket arms 106 are provided, with the arms106 arranged to be spaced around the centre point of the root end of ablade supported by said transport frame 100, such that the forcesassociated with said wind turbine blade are evenly transferred to thesupporting frame body 102.

The root end plate 104 is preferably arranged to couple with asubsection of the bolt circle of a wind turbine blade root end,resulting in a reduced height of the total structure of the transportframe 100. The embodiment of FIG. 11 shows the end plate 104 having asubstantially C-shaped structure, wherein the plate 104 is operable tocouple with approximately ⅔ of the bolt circle of a wind turbine bladeroot end. The shape and coupling of the root end plate 104 is selectedso as to adequately support a root end of a wind turbine blade, whilekeeping the height of the transport frame 100 structure to a minimum.

It will be understood that any other suitable shape of root end plate104 may be used, which is arranged to couple with a portion of a boltcircle of a wind turbine blade, e.g. a U-shaped plate, a substantiallysquare plate, etc.

It will be understood that the root end plate 104 may be provided with aplurality of coupling apertures arranged along separate notional boltcircles on the end plate 104, to accommodate the coupling of the rootend plate 104 to root ends of different wind turbine blades havingdifferent bolt circle diameters. This allows the root end transportframe 100 to be interchangeably used with wind turbine blades ofdifferent dimensions. It will further be understood that the couplingapertures may be shaped to be wider and/or longer than correspondingapertures in the bolt circle of a wind turbine blade, to allow foradjustment of coupling between the root end plate 104 and the blade rootend, for example in the event of misalignment, root end ovalisation,etc.

With reference to FIG. 12(a), an embodiment of a tip end transport frameaccording to an aspect of the invention is indicated generally at 108.The transport frame 108 comprises a base frame 110 and a support portion112 provided at the top of the base frame 110. The support portion 112comprises at least one tip end support bracket 114 which is hingedlycoupled to the transport frame 108. The support bracket 114 receives aportion of a wind turbine blade (indicated by section 116) to besupported by the tip end transport frame 108, wherein the blade portionis spaced from the tip end of the blade.

With reference to FIG. 12(b), an enlarged view is shown of an example ofa tip end support bracket 114. The bracket 114 comprises first andsecond ends 118 a,118 b arranged to couple with the support portion 112of the tip end transport frame 108. The bracket 114 further comprises acushioning or padding material 120 arranged to support the surface of awind turbine blade. A leading edge support lip 122 is provided on thebracket 114, preferably projecting from the cushioning or paddingmaterial 120. The leading edge support lip 122 is arranged to receivethe leading edge of a wind turbine blade supported on the bracket 114,to prevent movement of the blade when on the bracket 114.

In use, a first end 118 a of the bracket 114 may be attached to thesupport portion 112, with the second end 118 b projecting free of theframe. A portion 116 of a wind turbine blade can be placed on thebracket 114 with the leading edge of the blade fitted adjacent to saidlip 122. The bracket may then be pivoted relative to the transport framebody, to position the blade within the transport frame 108, at whichpoint the second end 118 b of the bracket 114 can be secured to theframe 108. A secondary support strap 124 may then be positioned over thesurface of the blade section 116 opposed the support bracket 114, andsecured to the support portion 112, to securely retain the wind turbineblade within the transport frame 108.

It will be understood that the support bracket 114 may be formed from arelatively flexible strap having a cushioning or padding material 120and a leading edge support lip 122 moulded onto the strap.

The base frame 110 of the tip end transport frame 108 has a height h.This ensures that the portion 116 of the wind turbine blade is supportedat a distance h from the ground or underlying surface. With reference toFIG. 13, this configuration of a transport system for a wind turbineblade provides additional advantages when used for the transportation orstorage of pre-bent wind turbine blades, where the wind turbine bladesare manufactured to have a curve or bend in a substantially upwinddirection, as described in European Patent No. EP1019631.

FIG. 13(a) illustrates a head-to-toe stacking arrangement of pre-bentwind turbine blades 128 using a transport system as shown in FIGS. 5 and9, provided on a surface S. In this case, the pre-bend of the windturbine blades 128 will result in the tip end 128 a of the bottom windturbine blade projecting beneath the surface level S for the transportsystem stack. Accordingly, the transport system stack must be providedon a platform raised in some manner from ground level, to ensure thatthe tip end 128 a of the bottom wind turbine blade is not damaged whenarranged in the stack. Such an arrangement can lead to additionalcomplications during handling and transportation of the stack.

By contrast, FIG. 13(b) illustrates a head-to-toe stacking arrangementof pre-bent wind turbine blades 128 using a transport system comprisingthe root end frame 100 and the tip end frame 108 of FIGS. 11 and 12,provided on a surface S. In this embodiment, as the tip end transportframe 108 supports the wind turbine blade section 116 at the top of thebase frame 110, at a distance h from the surface level S, accordinglythe tip end 128 of the bottom wind turbine blade is maintained above thesurface level S, removing the need for any additional raising of thetransport stack above the surface S.

The tip end transport frame is arranged to be positioned at a locationtowards, but spaced from, the tip end of a wind turbine blade.Preferably, the tip end transport frame is arranged to be positioned ata distance F from the root end of the blade, wherein (0.5 L)<F<(0.95 L),preferably (0.6 L)<F<(0.85 L). Supporting the tip portion of the windturbine blade at such a location in the outboard portion of the blade,spaced from the tip end, provides a balance between effectivelystructurally supporting the blade, while reducing the minimum effectivewheelbase or support surface needed to support the total transportsystem.

Furthermore, due to the reduced height of the root end transport frame100, the base frame 110 of subsequent tip end transport frames 108,which are stacked on preceding root end transport frames 100,effectively overlap with the root end of the wind turbine bladesupported on the preceding root end transport frames 100. Thisarrangement acts to reduce the overall height of the transport stack,while accommodating the adjusted dimensions of the tip end transportframes 108, providing for ease of handling and minimised spacerequirements for transportation.

Preferably, the combined height H of the root end transport frame 100and height h of the base frame 110 of the tip end transport frame 108 isapproximately equal to the bolt circle diameter distance of a windturbine blade to be supported by the transport frames 100,108.

The invention has been described with reference to preferredembodiments. However, the scope of the invention is not limited to theillustrated embodiments, and alterations and modifications can becarried out without deviating from the scope of the invention that isdefined by the following claims. The packaging system has for instancebeen described in relation to an L-shaped frame assembly. However, inanother advantageous embodiment, the frame assembly may be T-shaped sothat the root end bracket is attached to the tip end frame at anintermediate part thereof. Also, the blades may be stacked in apackaging system, where the root end frames and tip end frames arearranged in the same plane as shown in FIG. 10. The transportation andstorage system has also been described in a configuration, where thesecond wind turbine blade is arranged above the first wind turbineblade. However, it is clear that the system could also be arranged in aconfiguration, where the first and the second wind turbine blades arearranged side-by-side. In such a configuration, the blades would insteadbe arranged so that the bond lines and chord of the shoulder form anangle of approximately 25 degrees compared to vertical. Further, thereceptacles of the tip end frames could instead be adapted to supportthe leading edge of a tip end section instead.

The invention is not limited to the embodiments described herein, andmay be modified or adapted without departing from the scope of thepresent invention

LIST OF REFERENCE NUMERALS

-   2 wind turbine-   4 tower-   6 nacelle-   8 hub-   10 blade-   14 blade tip-   15 tip end section-   16 blade root-   17 root end face-   18 leading edge-   20 trailing edge-   22 pitch axis-   24 pressure side shell part/upwind shell part-   26 suction side shell part/downwind shell part-   28 bond lines-   29 horizontal-   30 root region-   32 transition region-   34 airfoil region-   50 airfoil profile-   52 pressure side/upwind side-   54 suction side/downwind side-   56 leading edge-   58 trailing edge-   60 chord-   62 camber line/median line-   70 first frame assembly-   71 root end frame/root end bracket (of first frame assembly)-   72 tip end frame/transversely extending frame part (of first frame    assembly)-   80 first frame assembly-   81 root end frame/root end bracket (of first frame assembly)-   82 tip end frame/transversely extending frame part (of first frame    assembly)-   90 intermediate protection member-   92 additional protection member-   100 root end transport frame-   102 frame body-   104 root end plate-   106 bracket arms-   108 tip end transport frame-   110 base frame-   112 support portion-   114 support bracket-   116 wind turbine blade portion-   118 support bracket end-   120 cushioned support material-   122 leading edge support lip-   124 retaining strap-   c chord length-   d_(t) position of maximum thickness-   d_(f) position of maximum camber-   d_(p) position of maximum pressure side camber-   f camber-   I_(f) longitudinal distance between root end frames-   I_(o) longitudinal extent of blade tip overhang-   L blade length-   r local radius, radial distance from blade root-   t thickness-   D blade root diameter-   Δy prebend-   H root end transport frame height-   W root end transport frame width-   D_(f) root end transport frame depth-   h tip end transport frame height

The invention claimed is:
 1. A transport system for a wind turbine bladehaving a tip end and a root end, the blade further having a bolt circlediameter D at said root end, wherein the transport system comprises: atleast one root end transport frame for supporting a root end of a windturbine blade; at least one tip end transport frame for supporting aportion of a wind turbine blade towards the tip end of said blade, saidtip end transport frame comprising a base frame and a support bracketprovided on top of said base frame for receiving a portion of a windturbine blade; wherein the tip end transport frame is stackable on topof the root end transport frame, such that the transport system isoperable to stack successive wind turbine blades in an alternating rootend to tip end arrangement; wherein said root end transport frame has aheight H; wherein the base frame of said tip end transport frame has aheight h; and wherein (H+h) is approximately equal to D, such that aroot end transport frame and the base frame of a successively stackedtip end transport frame overlap with a root end of a wind turbine bladesupported by said root end transport frame.
 2. The transport system ofclaim 1, wherein (0.5 D)<H<(0.9 D).
 3. The transport system of claim 1,wherein the root end transport frame has the height H, a width, and adepth, wherein the width of said root end transport frame is equal to orgreater than the bolt circle diameter of a wind turbine blade to besupported by said root end transport frame.
 4. The transport system ofclaim 1, wherein the root end transport frame has the height H, a width,and a depth, wherein the depth of said root end transport frame is equalto or greater than one quarter of the width of the root end transportframe.
 5. The transport system of claim 1, wherein the root endtransport frame comprises: a frame body; and a root end plate coupled tosaid frame body, said root end plate arranged to couple with a root endof a wind turbine blade, wherein said root end plate is arranged tocouple with less than ⅔ of a circumference of a bolt circle of a rootend of a wind turbine blade to support said wind turbine blade on saidroot end transport frame.
 6. The transport system of claim 5, whereinsaid root end plate comprises a substantially C-shaped body arranged tocouple with a portion of the bolt circle of a root end of a wind turbineblade.
 7. The transport system of claim 1, wherein the root endtransport frame comprises: a frame body; and a root end plate forcoupling to the root end of a wind turbine blade, wherein said root endplate is hingedly coupled to said frame body.
 8. The transport system ofclaim 7, wherein said root end plate is hingedly coupled to the framebody of said root end transport frame along a horizontal axis.
 9. Thetransport system of claim 7, wherein said root end plate is hingedlycoupled to the frame body of said root end transport frame along avertical axis.
 10. The transport system of claim 7, wherein said rootend plate is mounted on at least one bracket arm, said at least onebracket arm coupled to said root end transport frame via a hinged joint.11. The transport system of claim 10, wherein said at least one bracketarm comprises an articulated bracket.
 12. The transport system of claim10, wherein said root end transport frame comprises at least a first anda second bracket arm, wherein said first and second bracket arms arepositioned on opposed sides of a notional central longitudinal axis of awind turbine blade to be mounted to said root end plate.
 13. Thetransport system of claim 1, wherein the base frame of the at least onetip end transport frame includes a frame body; the support bracket ofthe at least one tip end transport frame includes at least one tip endsupport bracket for supporting a portion of a wind turbine blade towardsthe tip end of said blade, wherein a first end of said tip end supportbracket is hingedly coupled to said tip end transport frame along ahorizontal axis via a hinged coupling; and wherein a leading edgesupport lip is provided on said tip end support bracket, said leadingedge support lip arranged to receive a portion of the leading edge of awind turbine blade supported by said tip end support bracket, such thatthe wind turbine blade can be pivotably moved about said hinged couplingrelative to said tip end transport frame while supported on said tip endsupport bracket.
 14. The transport system of claim 13, wherein a secondend of said tip end support bracket can be releasably secured to theframe body of said tip end transport frame when said tip end supportbracket is received in said frame body.
 15. The transport system ofclaim 13, wherein said tip end support bracket comprises a flexiblestrap having a support surface provided on said flexible strap.
 16. Thetransport system of claim 13, wherein the tip end transport framefurther comprises a securing strap to be fitted around a wind turbineblade received in said tip end transport frame.
 17. The transport systemof claim 1, wherein said tip end transport frame is arranged to bepositioned at a location toward the tip end of a wind turbine blade tobe supported by the transport system, such that a sweep or bend of thewind turbine blade from the location of said tip end transport frame tothe tip end of the supported blade is less than height h of the baseframe of the tip end transport frame.
 18. The transport system of claim1, wherein a wind turbine blade to be supported by the transport systemhas a longitudinal length L, and wherein the tip end transport frame isarranged to be positioned at a distance F from the root end of saidblade, wherein (0.5 L) <F<(0.95 L).
 19. A method of transporting atleast two wind turbine blades having a tip end and a root end, themethod comprising the steps of: supporting a first wind turbine blade,wherein a first root end transport frame is arranged to support the rootend of said first wind turbine blade and a first tip end transport frameis arranged to support a portion of said first wind turbine bladetowards the tip end of said first wind turbine blade, said first windturbine blade having a bolt circle diameter D at said root end;supporting a second wind turbine blade, wherein a second root endtransport frame is arranged to support the root end of said second windturbine blade and a second tip end transport frame is arranged tosupport a portion of said second wind turbine blade towards the tip endof said second wind turbine blade, and stacking said second root endtransport frame on top of said first tip end transport frame, andstacking said second tip end transport frame on top of said first rootend transport frame, wherein said second wind turbine blade is stackedin an alternating root end to tip end arrangement above said first windturbine blade to form a unit for transport, wherein at least said firstroot end transport frame is arranged to have a height H, wherein saidfirst and second tip end transport frames are arranged to support therespective first and second wind turbine blades at a height h above abase of the first and second tip end transport frames, and wherein (H+h)is approximately equal to D, such that said first root end transportframe and at least a portion of said second tip end transport frameoverlap with the root end of said first wind turbine blade.
 20. Thetransport system of claim 1, wherein (0.5 D)<H<(0.75 D).
 21. Thetransport system of claim 1, wherein a wind turbine blade to besupported by the transport system has a longitudinal length L, andwherein the tip end transport frame is arranged to be positioned at adistance F from the root end of said blade, wherein (0.6 L)<F<(0.85 L).